Summary Pulmonary Hypertension

1 [Harrison’s 21st] 283. Pulmonary Hypertension

Pulmonary hypertension (PH)
- Heterogenous disease involving pathogenic remodeling of the pulmonary vasculature, which
increases pulmonary artery pressure and vascular resistance
- Left heart or primary lung disease
o Most common cause
- Observed in some patients as a late complication of luminal pulmonary embolism
- Pulmonary arterial hypertension (PAH)
o Uncommon
o Distinct, PH subtype characterized by the interplay between molecular and genetic
events that cause an obliterative arteriopathy and symptoms of dyspnea, chest
pain, and syncope
- If left untreated
o Carries a high mortality rate, largely owing to decompensated right heart failure
- Mean pulmonary artery pressure (mPAP) used to diagnose PH
o Lowered from > 25 mmHg to > 20 mmHg
 Adjustment emphasizes earlier detection of PH, as a substantial
delay in diagnosis of up to 2 years is common
 Has important implications for both quality of life and life span


PATHOBIOLOGY DIAGNOSIS

- Underlie the pathogenesis of PAH: - Findings often overlooked
 Apoptosis resistance - Symptoms are nonspecific, insidious, and overlap considerably with many common conditions
 Cell proliferation
 Dysregulated metabolism - Present with dyspnea and/or fatigue
 Increased oxidant stress involving pulmonary vascular cells and - Less common and associated with more advanced disease:
adventitial fibroblasts o Edema
o Events lead to hypertrophic, fibrotic, and plexogenic remodeling of distal (small) o Chest pain
pulmonary arterioles, which decreases vascular compliance and promotes in situ o Presyncope
thrombosis o Syncope
- Vasoconstriction-dominant phenotype - Early phases of PAH
o Minority of patients o Physical examination is often unrevealing
o Requires a unique treatment strategy
- Disease progresses
- Abnormalities in multiple molecular pathways and genes that regulate pulmonary vascular
o Evidence of right ventricular failure with elevated jugular venous pressure, lower
endothelial and smooth muscles: extremity edema, and ascites
o Decreased expression of the voltage-regulated potassium channel
o Mutations in the bone morphogenetic protein receptor-2 - Cardiovascular examination
o Increased tissue factor expression o May reveal an accentuated P2 component of the second heart sound, a right-sided
o Overactivation of the serotonin transporter S3 or S4, and a holosystolic tricuspid regurgitant murmur
o Hypoxia-induced activation of hypoxia-inducible factor-1a - Seek signs of the diseases that are commonly concurrent PH:
o Activation of nuclear factor of activated T cells o Clubbing
- May amplify the obliterative arteriopathy  Seen in some chronic lung diseases
o Thrombin deposition in the pulmonary vasculature that develops as an o Sclerodactyly and telangiectasia
independent abnormality  Signify scleroderma or the limited cutaneous for, CREST (calcinosis,
o As a result of endothelial dysfunction Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, and
telangiectasia)
o Crackles on examination of the lungs and systemic hypertension
PATHOPHYSIOLOGY  May be clues to left-sided systolic or diastolic heart failure


- In PAH:
OVERVIEW OF THE DIAGNOSTIC CLINICAL EVALUATION
o Pathologic changes to pulmonary arterial compliance
 Result in a progressive increase in total pulmonary vascular
resistance (PVR) - Electrocardiography
o Right ventricular hypertrophy or stain
- Resting PVR
o Increases through the temporal progression of PAH - Enlargement of pulmonary arteries and obliteration of the retrosternal space
o Often observed on chest roentgenography
- Preserve cardiac output (CO) in the face of elevated right ventricular afterload
o Right ventricular work must increase - Echocardiography with agitated saline (bubble) study
o Most important initial screening test
- Sustained (or progressive) increase in right ventricular work
o Causes a shift in the efficiency of right ventricular systolic function by which - Elevated estimated pulmonary artery systolic pressure (> 35 mmHg) or a hypertrophied or
maintaining pulmonary circulatory pressure depletes myocardial energy dilated right ventricular
 Changes occur at the expense of energy normally reserved to o Support the diagnosis of PH
maintain optimal blood perfusion through the alveolar-capillary - Specific etiologies of PH
interface for blood oxygenation o Valvular disease
 Right ventricular-pulmonary arterial uncoupling o Left ventricular systolic and diastolic function
- End-stage PAH o Left atrial enlargement
o CO declines, leading to a decrease in mPAP o Intracardiac shunt
o Extravascular manifestations are frequent - Patients with evidence of PH on echocardiography or in whom unexplained dyspnea or
 Overactivation of neurohumoral signaling hypoxemia is evident despite an unremarkable echocardiogram
 Renal failure o Often require further assessment
 Volitional muscle atrophy
 Due to deconditioning - Additional tests focusing functional capacity
o Useful for quantifying disease burden
 6-minute walk distance (6-MWD) assessment
 Aids in assessing prognosis prognosis
- Cardiopulmonary exercise testing (CPET)
o Differentiates between cardiac and pulmonary causes of dyspnea
o Includes:
 Measuring peak volume of oxygen consumption
 Integrated parameter of cardiopulmonary fitness
 Useful in prognosticating PH
o Patients with normal CPET
 Further invasive testing is often necessary
 Exception:
o Patients with reassuring CPET results
but in whom a significant decrease in
exercise tolerance from baseline is
nonetheless reported
 Often observed in elite
athletes or highly

, 2 [Harrison’s 21st] 283. Pulmonary Hypertension

conditioned individuals o Lowers NT-proBNP levels in PAH
with early-stage PH o May be used as a biomarker for assessing treatment response in clinical practice
- Invasive hemodynamic monitoring with right heart catheterization (RHC)
o Gold standard for PH diagnosis and severity assessment
o Interpretation often optimized by information from diagnostic tests that support
and frame the clinical context of pulmonary vascular disease INVASIVE CARDIOPULMONARY HEMODYNAMICS
- RHC
STEPWISE APPROACH TO DIAGNOSING PH o Remains the gold standard test to both establish the diagnosis of PH and guide
selection of appropriate medical therapy
- Patients with a string history of inhaled tobacco use - Hemodynamic criteria for diagnosing PH:
o May benefit from prioritizing diagnostic tests assessing pulmonary function and the o Require an mPAP >20 mmHg
lung parenchyma
- Precapillary and postcapillary PH
- Myocardial ischemia evaluation o Distinguished by virtue of a pulmonary artery wedge pressure (PAWP)(or left
o Should be considered early in the evaluation of patients with left-sided ventricular of a pulmonary artery wedge pressure (LVEDP) < 15 mmHg or > 15
cardiomyopathy mmHg
- Isolated precapillary PH
o Requires a PVR > 3.0 Wood units (WU)
PULMONARY FUNCTION AND LUNG IMAGING
- Isolated postcapillary PH
- Pulmonary function testing results o Defined by PVR <3.0 WU
o May suggest restrictive or obstructive lung diseases as the cause of dyspnea or PH - Combined pre- and postcapillary PH
- PAH o Recognized, defined by elevated mPAP >20 mmHg, PVR > 3.0 WU, and PAWP >15
o Isolated reduction in diffusing capacity of the lungs for carbon monoxide (DL CO) mmHg
 Classic finding
- High-resolution computed tomography (CT)
o Provides useful information, particularly enlargement of the main pulmonary
artery, right ventricle, and atria, as well as peripheral pruning of small vessels
o May also reveal signs of venous congestion including centrilobular ground glass
infiltrate and thickened septa
- Absence of left heart disease
o Suggest pulmonary venous disease
 Rare cause of PAH that can be quite challenging to diagnose
- CT - Hemodynamic profiles
o Critical for distinguishing co-morbid interstitial lung disease, emphysema, or overlap o Inform PH clinical categorization
syndromes that include fibrosis and obstructive pulmonary disease o Isolated precapillary PH
 Most often due to primary lung disease, PAH, or CTEPH
o Isolated postcapillary PH
SLEEP STUDIES  Occurs in patients with mitral valvular disease, left ventricular
systolic dysfunction, or heart failure with preserved ejection faction
- Nocturnal desaturation - Same etiologies for isolated postcapillary PH
o Common finding in PH, even in the absence of sleep-disordered breathing o Underlie combined pre and postcapillary PH
- All patients  Indicates that chronic vascular congestion due to left atrial
o Should undergo nocturnal oximetry screening, regardless of whether classic hypertension has resulted in substantial pulmonary vascular
symptoms of obstructive sleep apnea or obesity-hypoventilation syndrome are remodeling
present - Vasoreactivity testing
o Should be reserved mainly for patients with idiopathic or hereditary PAH

ASSESSMENT OF PULMONARY ARTERIAL THROMBOSIS - Vasodilators with a short duration of action
 Inhaled nitric oxide (NO)
 Inhaled epoprostenol
- Patients with prior luminal pulmonary embolism
o Preferred for testing
o Increased risk for chronic thromboembolic pulmonary hypertension (CTEPH)
 Specific PH subtype characterized by vascular fibrosis and arterial - Decrease in mPAP by > 10 mmHg to an absolute level <40 mmHg without a decrease in CO
microthrombus o Positive pulmonary vasodilator response
 Curable in many patients by surgical endarterectomy  Considered for long-term treatment with calcium channel blockers
 Widely underdiagnosed - Less than 5% of patients
- Ventilation-perfusion (V/Q) scanning o Deemed vasoreactive
o Primary test used to screen and diagnose CTEPH o Prognosis among these patients is particularly favorable
 Should be considered in any patient with PH of unclear etiology
- CT angiography
o Commonly used to stage anatomic thromboembolic burden which may be
PULMONARY HYPERTENSION CLASSIFICATION
ultimately necessary to determine operative candidacy
- Pulmonary angiography
o Definitive diagnostic procedure
o Contrast enhancement in this study provides detailed information on webbing,
stricture, and vascular tapering patterns pathognomonic for CTEPH


SEROLOGY
- Human immunodeficiency virus (HIV) test
o Laboratory data that are important for screening
o When clinically indicated
- All patients - PH clinical classification schema
o Should have antinuclear antibodies, rheumatoid factor, and anti-Scl-70 antibodies o Formulated
assessed to screen for the most common rheumatologic diseases associated with o According to similarities in pathophysiologic mechanisms and clinical presentation
PH - Current classification system
- Liver function and hepatitis serology tests o Last revised in 2018 during the Sixth World Symposium on Pulmonary
o Important to screen for underlying liver disease Hypertension, recognizes five PH categories listed here sequentially as groups 1-5:
 PAH
- Methamphetamine use
 PH due to left heart disease
o Recognized increasingly as a cause of PAH
 PH due to chronic lung disease, or sleep-disordered breathing
- Screening  CTEPH
o Should be considered in patients from endemic regions or in whom the cause of  Group of miscellaneous diseases that rarely cause PH
PAH is not otherwise established
- Brain natriuretic peptide (BNP) and the N-terminus of its pro-peptide (NT-proBNP)
o Correlate with right ventricular (dys) function, hemodynamic severity, and
PULMONARY ARTERIAL HYPERTENSION
functional status in PAH
- WHO group 1 PH or PAH
- Medical therapy
o Involves marked pulmonary arterial precapillary remodeling including: